Mycophenolate mofetil prevents arteriolopathy and renal injury in subtotal ablation despite persistent hypertension

A novel method for comparison of arterial remodeling in hypertension: Quantification of arterial trees and recognition of remodeling patterns on histological sections

Remodeling of spatially heterogeneous arterial trees is routinely quantified on tissue sections by averaging linear dimensions, with lack of comparison between different organs and models. The impact of experimental models or hypertension treatment modalities on organ-specific vascular remodeling remains undefined. A wide variety of arterial remodeling types has been demonstrated for hypertensive models, which include differences across organs. The purpose of this study was to reassess methods for measurement of arterial remodeling and to establish a morphometric algorithm for standard and comparable quantification of vascular remodeling in hypertension in different vascular beds. We performed a novel and comprehensive morphometric analysis of terminal arteries in the brain, heart, lung, liver, kidney, spleen, stomach, intestine, skin, skeletal muscle, and adrenal glands of control and Goldblatt hypertensive rats on routinely processed tissue sections. Mean dimensions were highly variable but grouping them into sequential 5 μm intervals permitted creation of reliable linear regression equations and complex profiles. Averaged arterial dimensions demonstrated seven remodeling patterns that were distinct from conventional inward-outward and hypertrophic-eutrophic definitions. Numerical modeling predicted at least nineteen variants of arterial spatial conformations. Recognition of remodeling variants was not possible using averaged dimensions, their ratios, or the remodeling and growth indices. To distinguish remodeling patterns, a three-dimensional modeling was established and tested. The proposed algorithm permits quantitative analysis of arterial remodeling in different organs and may be applicable for comparative studies between animal hypertensive models and human hypertension. Arterial wall tapering is the most important factor to consider in arterial morphometry, while perfusion fixation with vessel relaxation is not necessary. Terminal arteries in organs undergo the same remodeling pattern in Goldblatt rats, except for organs with hemodynamics affected by the arterial clip. The existing remodeling nomenclature should be replaced by a numerical classification applicable to any type of arterial remodeling.

Salvianolic Acid A Protects the Kidney against Oxidative Stress by Activating the Akt/GSK-3β/Nrf2 Signaling Pathway and Inhibiting the NF-κB Signaling Pathway in 5/6 Nephrectomized Rats

Salvianolic acid A (SAA) is a bioactive polyphenol extracted from Salviae miltiorrhizae Bunge, which possesses a variety of pharmacological activities. In our previous study, we have demonstrated that SAA effectively attenuates kidney injury and inflammation in an established animal model of 5/6 nephrectomized (5/6Nx) rats. However, there has been limited research regarding the antioxidative effects of SAA on chronic kidney disease (CKD). Here, we examined the antioxidative effects and underlying mechanisms of SAA in 5/6Nx rats. The rats were injected with SAA (2.5, 5, and 10 mg·kg⁻¹·d⁻¹, ip) for 28 days. Biochemical, flow cytometry, and Western blot analyses showed that SAA significantly increased the activities of total superoxide dismutase (T-SOD), glutathione peroxidase (GPx), and catalase (CAT) and lowered the levels of malondialdehyde (MDA), reactive oxygen species (ROS), and NADPH oxidase 4 (NOX-4) in a dose-dependent manner in 5/6Nx rats and in H₂O₂-induced HK-2 cells in vitro. Moreover, SAA enhanced the activation of the protein kinase B/glycogen synthase kinase-3β/nuclear factor-erythroid-2-related factor 2 (Akt/GSK-3β/Nrf2) signaling pathway in a dose-dependent manner and subsequently increased the expression of heme oxygenase-1 (HO-1) in the kidney of 5/6Nx rats, which were consistent with those obtained in H₂O₂-induced HK-2 cells in vitro shown by Western blot analysis. Furthermore, SAA significantly increased the expression of intranuclear Nrf2 and HO-1 proteins compared to HK-2 cells stimulated by LPS on the one hand, which can be enhanced by QNZ to some extent; on the other hand, SAA significantly lowered the expression of p-NF-κB p65 and ICAM-1 proteins compared to HK-2 cells stimulated by H₂O₂, which can be abrogated by ML385 to some extent. In conclusion, our results demonstrated that SAA effectively protects the kidney against oxidative stress in 5/6Nx rats. One of the pivotal mechanisms for the protective effects of SAA on kidney injury was mainly related with its antioxidative roles by activating the Akt/GSK-3β/Nrf2 signaling pathway and inhibiting the NF-κB signaling pathway.

Salvianolic acid A attenuates kidney injury and inflammation by inhibiting NF-κB and p38 MAPK signaling pathways in 5/6 nephrectomized rats

Salvianolic acid A (SAA) is a minor phenolic carboxylic acid extracted from Salviae miltiorrhizae Bunge (Danshen). SAA exhibits a variety of pharmacological activities, such as antioxidative, anti-thrombotic, neuroprotective, and anti-fibrotic effects, as well as protection from myocardial ischemia and prevention of diabetes and other diseases. Furthermore, SAA has shown renal-protective effects in doxorubicin-induced nephropathy. However, there has been limited research regarding the effects of SAA and underlying mechanisms in chronic kidney disease (CKD). Here, we examined the effects and molecular mechanisms of SAA in an established animal model of 5/6 nephrectomized (5/6Nx) rats. The rats were injected with SAA (2.5, 5, and 10 mg/kg per day, intraperitoneally (ip)) for 28 days. SAA dose-dependently lowered the levels of urine protein, blood urea nitrogen, serum creatinine, plasma total cholesterol, and plasma triglycerides in 5/6Nx rats. Histological examination revealed that SAA dose-dependently attenuated renal pathological lesions, evidenced by reduced renal tubulointerstitial fibrosis by decreasing the expression levels of tumor growth factor-β1 and α-smooth muscle actin in 5/6Nx rats. Moreover, SAA dose-dependently inhibited the activation of nuclear factor-κB (NF-κB) and p38 mitogen-activated protein kinase (MAPK) signaling pathways, subsequently attenuating the secretion of tumor necrosis factor-α and interleukin-1β and inhibiting the expression of monocyte chemotactic protein-1, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 in kidneys of 5/6Nx rats. The above results were consistent with those obtained in lipopolysaccharide-induced HK-2 cells in vitro (a recognized in vitro inflammatory model). In conclusion, our results demonstrated that SAA effectively attenuates kidney injury in 5/6Nx rats. The therapeutic effects of SAA on kidney injury can be attributed to its anti-inflammatory activities through inhibition of the activation of the NF-κB and p38 MAPK signaling pathways.

Inhibition of SREBP With Fatostatin Does Not Attenuate Early Diabetic Nephropathy in Male Mice

Sterol regulatory element binding protein (SREBP) is an important potential mediator of kidney fibrosis and is known to be upregulated in diabetic nephropathy. We evaluated the effectiveness of SREBP inhibition as treatment of diabetic nephropathy. Type 1 diabetes was induced in uninephrectomized male CD1 mice with streptozotocin. The mice were treated with the SREBP inhibitor fatostatin for 12 weeks. At the endpoint, kidney function and pathologic findings were assessed. Fatostatin inhibited the increase of both isoforms of SREBP (types 1 and 2) in diabetic kidneys. Treatment attenuated basement membrane thickening but did not improve hyperfiltration, albuminuria, or kidney fibrosis in diabetic mice. The treatment of nondiabetic mice with fatostatin led to hyperfiltration and increased the glomerular volume to levels seen in diabetic mice. This was associated with increased renal inflammation and a trend toward increased renal fibrosis. Both in vivo and in cultured renal proximal tubular epithelial cells, fatostatin increased the expression of the proinflammatory cytokine monocyte chemoattractant protein-1. Thus, SREBP inhibition with fatostatin not only is ineffective in preventing diabetic nephropathy but also leads to kidney injury in nondiabetic mice. Further research on the efficacy of other SREBP inhibitors and the specific roles of SREBP-1 and SREBP-2 in the treatment and pathogenesis of diabetic nephropathy is needed.

Long-term treatment with chaethomellic acid A reduces glomerulosclerosis and arteriolosclerosis in a rat model of chronic kidney disease

The high prevalence of end-stage renal disease emphasizes the failure to provide therapies to effectively prevent and/or reverse renal fibrosis. Therefore, the aim of this study was to evaluate the effect of long-term treatment with chaethomellic acid A (CAA), which selectively blocks Ha-Ras farnesylation, on renal mass reduction-induced renal fibrosis. Male Wistar rats were sham-operated (SO) or subjected to 5/6 renal mass reduction (RMR). One week after surgery, rats were placed in four experimental groups: SO:SO rats without treatment (n=13); SO+CAA: SO rats treated with CAA (n=13); RMR:RMR rats without treatment (n=14); and RMR+CAA:RMR rats treated with CAA (n=13). CAA was intraperitoneally administered in a dose of 0.23μg/kg three times a week for six months. Renal fibrosis was evaluated by two-dimensional ultrasonography and histopathological analysis. The kidneys of the RMR animals treated with CAA showed a significantly decrease in the medullary echogenicity (p<0.05) compared with the RMR rats that received no treatment. Glomerulosclerosis and arteriolosclerosis scores were significantly lower (p<0.001) in the RMR+CAA group when compared with the RMR group. There were no significant differences in interstitial fibrosis, interstitial inflammation and tubular dilatation scores between the RMR+CAA and RMR groups. These data suggest that CAA can be a potential future drug to attenuate the progression of chronic kidney disease.

Effect of mycophenolic acid in experimental, nontransplant glomerular diseases: new mechanisms beyond immune cells

Mycophenolic acid (MPA) was introduced into clinical practice as immunosuppressive drug therapy to prevent allograft rejection. Since then, its clinical application has widened. Our goal was to review the lessons learned from experimental nontransplant glomerular disease models on the mechanisms of MPA therapy. T and B lymphocytes are preferentially dependent on de novo purine synthesis. By inhibiting the rate-limiting enzyme of de novo purine synthesis, MPA depletes the pool of deoxyguanosine triphosphate (dGTP) and inhibits proliferation of these immune cells. Furthermore, MPA can also induce apoptosis of immune cells and is known to inhibit synthesis of fucose- and mannose-containing membrane glycoproteins altering the surface expression and binding ability of adhesion molecules. However, MPA exerts a direct effect also on nonimmune cells. Mesangial cells are partially dependent on de novo purine biosynthesis and are thus susceptible to MPA treatment. Additionally, MPA can inhibit apoptosis in podocytes and seems to be beneficial in preserving the expression of nephrin and podocin, and by attenuation of urokinase receptor expression leads to decreased foot-process effacement. In summary, our manuscript sheds light on the molecular mechanisms underlying the antiproteinuric effect of MPA. Overall, MPA is an excellent treatment option in many immunologic glomerulopathies because it possesses immunosuppressive properties, has a remarkable effect on nonimmune cells and counteracts the proliferation of mesangial cells, expansion of mesangial matrix, and foot-process effacement of podocytes combined with a low systemic toxicity.

The Effects of Long-Term Chaetomellic Acid A Administration on Renal Function and Oxidative Stress in a Rat Model of Renal Mass Reduction

Purpose. This study aimed to evaluate the effect of chronic treatment with chaetomellic acid A (CAA) on oxidative stress and renal function in a model of renal mass reduction. Methods. Male Wistar rats were subjected to 5/6 nephrectomy (RMR) or sham-operated (SO). One week after surgery, rats have been divided into four experimental groups: RMR: RMR rats without treatment (n = 14); RMR + CAA: RMR rats treated with CAA (n = 13); SO: SO rats without treatment (n = 13); and SO + CAA: SO rats treated with CAA (n = 13). CAA was intraperitoneally administered in a dose of 0.23 µg/Kg three times a week for six months. Results. RMR was accompanied by a significant reduction in catalase and glutathione reductase (GR) activity (p < 0.05) and a decrease in reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio. CAA administration significantly increased catalase and GR activity (p < 0.05) and increased GSH/GSSG ratio, but no significant difference between the treated and nontreated groups was found in this ratio. No significant differences were found between the RMR groups in any of the parameters of renal function. However, CAA administration slightly improves some parameters of renal function. Conclusions. These data suggest that CAA could attenuate 5/6 RMR-induced oxidative stress.

Mycophenolate mofetil and curcumin provide comparable therapeutic benefit in experimental chronic kidney disease: role of Nrf2-Keap1 and renal dopamine pathways

Increased oxidative stress and inflammation have an important role in the pathophysiology of chronic kidney disease (CKD). On the other hand, more affordable therapeutic alternatives for treating this disease are urgently needed. Therefore, we compared the therapeutic efficacy of curcumin and mycophenolate mofetil (MMF) in 5/6 nephrectomy (5/6 Nx) model of CKD. Also, we evaluated whether both compounds provide benefit through the preservation of similar antioxidant mechanisms. Four groups of male Wistar were studied over a period of 4 wk. Control sham group (n= 12), 5/6 Nx (n = 12), 5/6 Nx + MMF (30 mg/k BW/day, n = 11) and 5/6 Nx + Curcumin (120 mg/k BW/day, n = 12). Renal function and markers of oxidative stress and inflammation were evaluated. Also Nrf2-Keap1 and renal dopamine, antioxidant pathways were assessed. 5/6 Nx induced an altered renal autoregulation response, proteinuria, and hypertension; these effects were in association with increased oxidative stress, endothelial dysfunction and renal inflammation. The mechanisms associated with these alterations included a reduced nuclear translocation of Nrf2 and hyperphosphorylation of dopamine D1 receptor with a concurrent overactivation of renal NADPH oxidase. Treatments with MMF and curcumin provided equivalent therapeutic efficacy as both prevented functional renal alterations as well as preserved antioxidant capacity and avoided renal inflammatory infiltration. Moreover, both treatments preserved Nrf2-Keap1 and renal dopamine antioxidant pathways. In summary, therapeutic strategies aimed to preserve renal antioxidant pathways can help to retard the progression of CKD.

Renal autoregulation in health and disease

Intrarenal autoregulatory mechanisms maintain renal blood flow (RBF) and glomerular filtration rate (GFR) independent of renal perfusion pressure (RPP) over a defined range (80-180 mmHg). Such autoregulation is mediated largely by the myogenic and the macula densa-tubuloglomerular feedback (MD-TGF) responses that regulate preglomerular vasomotor tone primarily of the afferent arteriole. Differences in response times allow separation of these mechanisms in the time and frequency domains. Mechanotransduction initiating the myogenic response requires a sensing mechanism activated by stretch of vascular smooth muscle cells (VSMCs) and coupled to intracellular signaling pathways eliciting plasma membrane depolarization and a rise in cytosolic free calcium concentration ([Ca(2+)]i). Proposed mechanosensors include epithelial sodium channels (ENaC), integrins, and/or transient receptor potential (TRP) channels. Increased [Ca(2+)]i occurs predominantly by Ca(2+) influx through L-type voltage-operated Ca(2+) channels (VOCC). Increased [Ca(2+)]i activates inositol trisphosphate receptors (IP3R) and ryanodine receptors (RyR) to mobilize Ca(2+) from sarcoplasmic reticular stores. Myogenic vasoconstriction is sustained by increased Ca(2+) sensitivity, mediated by protein kinase C and Rho/Rho-kinase that favors a positive balance between myosin light-chain kinase and phosphatase. Increased RPP activates MD-TGF by transducing a signal of epithelial MD salt reabsorption to adjust afferent arteriolar vasoconstriction. A combination of vascular and tubular mechanisms, novel to the kidney, provides for high autoregulatory efficiency that maintains RBF and GFR, stabilizes sodium excretion, and buffers transmission of RPP to sensitive glomerular capillaries, thereby protecting against hypertensive barotrauma. A unique aspect of the myogenic response in the renal vasculature is modulation of its strength and speed by the MD-TGF and by a connecting tubule glomerular feedback (CT-GF) mechanism. Reactive oxygen species and nitric oxide are modulators of myogenic and MD-TGF mechanisms. Attenuated renal autoregulation contributes to renal damage in many, but not all, models of renal, diabetic, and hypertensive diseases. This review provides a summary of our current knowledge regarding underlying mechanisms enabling renal autoregulation in health and disease and methods used for its study.

Urinary excretion of neutrophil gelatinase-associated lipocalin in diabetic rats

Recent studies suggest that tubular damage precedes glomerular damage in the progression of diabetic nephropathy. Therefore, we evaluated oxidative stress and urinary excretion of tubular proteins as markers of tubular dysfunction. Methods. Diabetes was induced in rats by streptozotocin administration (50 mg/kg). Oxidative stress was assessed by measuring the activity of catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD); additionally, expression levels of 3-nitrotyrosine (3-NT), 4-hydroxynonenal (4-HNE), and oxidized protein (OP) were quantified. Whole glomerular filtration rate (GFR) was measured. Urinary excretion of neutrophil gelatinase-associated lipocalin (uNGAL), osteopontin (uOPN), and N-acetyl-β-D-glucosaminidase (uNAG) was also determined. Results. Diabetic rats showed an increase in uNGAL excretion 7 days following induction of diabetes. Diuresis, proteinuria, albuminuria, creatinine clearance, and GFR were significantly increased by 30 days after induction. Furthermore, there was an increase in both CAT and SOD activity, in addition to 3-NT, 4-HNE, and OP expression levels. However, GPx activity was lower. Serum levels of NGAL and OPN, as well as excretion levels of uNGAL, uOPN, and uNAG, were increased in diabetics. Tubular damage was observed by 7 days after diabetes induction and was further aggravated by 30 days after induction. Conclusion. The tubular dysfunction evidenced by urinary excretion of NGAL precedes oxidative stress during diabetes.

Colchicine attenuates renal injury in a model of hypertensive chronic kidney disease

Hypertension is a risk factor for chronic kidney disease, particularly when associated with impaired renal autoregulation and thereby increased intraglomerular pressure (Pgc). Elevated Pgc can be modeled in vitro by exposing glomerular mesangial cells to mechanical strain. We previously showed that RhoA mediates strain-induced matrix production. Here, we show that RhoA activation is dependent on an intact microtubule network. Upregulation of the profibrotic cytokine connective tissue growth factor (CTGF) by mechanical strain is dependent on RhoA activation and inhibited by microtubule disruption. We tested the effects of the microtubule depolymerizing agent colchicine in 5/6 nephrectomized rats, a model of chronic kidney disease driven by elevated Pgc. Colchicine inhibited glomerular RhoA activation and attenuated both glomerular sclerosis and interstitial fibrosis without affecting systemic blood pressure. Upregulation of the matrix proteins collagen I and fibronectin, as well as CTGF, was attenuated by colchicine. Activity of the profibrotic cytokine TGF-β, as assessed by Smad3 phosphorylation, was also inhibited by colchicine. Microtubule disruption significantly decreased renal infiltration of lymphocytes and macrophages. Our studies thus indicate that colchicine modifies hypertensive renal fibrosis. Its protective effects are likely mediated by inhibition of RhoA signaling and renal infiltration of inflammatory cells. Already well-established in clinical practice for other indications, prevention of hypertension-associated renal fibrosis may represent a new potential use for colchicine.

Curcumin maintains cardiac and mitochondrial function in chronic kidney disease

Curcumin, a natural pigment with antioxidant activity obtained from turmeric and largely used in traditional medicine, is currently being studied in the chemoprevention of several diseases for its pleiotropic effects and nontoxicity. In chronic renal failure, the pathogenic mechanisms leading to cardiovascular disorders have been associated with increased oxidative stress, a process inevitably linked with mitochondrial dysfunction. Thus, in this study we aimed at investigating if curcumin pretreatment exerts cardioprotective effects in a rat model of subtotal nephrectomy (5/6Nx) and its impact on mitochondrial homeostasis. Curcumin was orally administered (120mg/kg) to Wistar rats 7 days before nephrectomy and after surgery for 60 days (5/6Nx+curc). Renal dysfunction was detected a few days after nephrectomy, whereas changes in cardiac function were observed until the end of the protocol. Our results indicate that curcumin treatment protects against pathological remodeling, diminishes ischemic events, and preserves cardiac function in uremic rats. Cardioprotection was related to diminished reactive oxygen species production, decreased oxidative stress markers, increased antioxidant response, and diminution of active metalloproteinase-2. We also observed that curcumin's cardioprotective effects were related to maintaining mitochondrial function. Aconitase activity was significantly higher in the 5/6Nx + curc (408.5±68.7nmol/min/mg protein) than in the 5/6Nx group (104.4±52.3nmol/min/mg protein, P<0.05), and mitochondria from curcumin-treated rats showed enhanced oxidative phosphorylation capacities with both NADH-linked substrates and succinate plus rotenone (3.6±1 vs 1.1±0.9 and 3.1±0.7 vs 1.2±0.8, respectively, P<0.05). The mechanisms involved in cardioprotection included both direct antioxidant effects and indirect strategies that could be related to protein kinase C-activated downstream signaling.

Curcumin reverses glomerular hemodynamic alterations and oxidant stress in 5/6 nephrectomized rats

The administration of curcumin before and throughout the study attenuates oxidant stress and glomerular hemodynamic alterations induced by 5/6 nephrectomy (5/6NX). The purpose of this work was to study if curcumin is able to reverse established glomerular hemodynamic alterations (e.g. hyperfiltration and glomerular hypertension) and oxidant stress in rats with 5/6NX. Curcumin (120 mg/kg) was given to rats with established renal injury (30 days after surgery) and continued for 30 days (days 31-60 of the study). All rats were studied on day 60 after surgery. Curcumin was able (a) to reverse 5/6NX-induced glomerular hypertension and hyperfiltration, (b) to induce cell proliferation and nuclear translocation of Nrf2 and (c) to reverse 5/6NX-induced oxidant stress and decrease in antioxidant enzymes. These beneficial effects of curcumin were associated with the ability of this antioxidant to reverse renal structural alterations, proteinuria, hypertension, interstitial fibrosis, fibrotic glomeruli, tubular atrophy and mesangial expansion. It has been shown for the first time that curcumin is able to reverse established oxidants stress glomerular hypertension and hyperfiltration in rats with 5/6NX. These novel findings may play a key role in the attenuation of proteinuria and progression of renal damage in rats with 5/6NX. These data suggest that curcumin may be useful to reverse established hemodynamic alterations and renal injury in patients with chronic renal failure.

Synergistic effect of uricase blockade plus physiological amounts of fructose-glucose on glomerular hypertension and oxidative stress in rats

Fructose in sweetened beverages (SB) increases the risk for metabolic and cardiorenal disorders, and these effects are in part mediated by a secondary increment in uric acid (UA). Rodents have an active uricase, thus requiring large doses of fructose to increase plasma UA and to induce metabolic syndrome and renal hemodynamic changes. We therefore hypothesized that the effects of fructose in rats might be enhanced in the setting of uricase inhibition. Four groups of male Sprague-Dawley rats (n = 7/group) were studied during 8 wk: water + vehicle (V), water + oxonic acid (OA; 750 mg/k BW), sweetened beverage (SB; 11% fructose-glucose combination) + V, and SB + OA. Systemic blood pressure, plasma UA, triglycerides (TG), glucose and insulin, glomerular hemodynamics, renal structural damage, renal cortex and liver UA, TG, markers of oxidative stress, mitDNA, fructokinase, and fatty liver synthase protein expressions were evaluated at the end of the experiment. Chronic hyperuricemia and SB induced features of the metabolic syndrome, including hypertension, hyperuricemia, hyperglycemia, and systemic and hepatic TG accumulation. OA alone also induced glomerular hypertension, and SB alone induced insulin resistance. SB + OA induced a combined phenotype including metabolic and renal alterations induced by SB or OA alone and in addition also acted synergistically on systemic and glomerular pressure, plasma glucose, hepatic TG, and oxidative stress. These findings explain why high concentrations of fructose are required to induce greater metabolic changes and renal disease in rats whereas humans, who lack uricase, appear to be much more sensitive to the effects of fructose.

Impaired post-infarction cardiac remodeling in chronic kidney disease is due to excessive renin release

The complex pathophysiological interactions between heart and kidney diseases are collectively known as cardiorenal syndrome. The renin-angiotensin system (RAS) may have a pivotal role in the development of cardiorenal syndrome. The aim of this study was to elucidate the RAS activity responsible for adverse post-infarction remodeling and prognosis in mice with renal failure. To establish the type IV cardiorenal syndrome model, 5/6 nephrectomy (NTX) was performed in a surgical procedure, followed by the induction of myocardial ischemia (MI) by a coronary artery ligation 4 weeks later. NTX and MI resulted in deteriorated left ventricular remodeling and RAS activation, which was improved by an aliskiren that appeared to be independent of renal function and blood pressure (BP). Moreover, MI induced in renin and angiotensinogen double-transgenic (Tg) mice showed comparable effects to MI plus NTX mice, including advanced ventricular remodeling and enhancement of RAS, oxidative stress, and monocytes chemoattractant protein (MCP)-1. Aliskiren suppressed these changes in the MI-induced Tg mice. In in vitro study, Nox2 expression was elevated by the stimulation of plasma from NTX mice in isolated neonatal cardiomyocytes. However, Nox2 upregulation was negated when we administered plasma from aliskiren-treated-NTX mice or isolated cardiomyocytes from AT1-deficient mice. Primary mononuclear cells also showed an upregulation in the expression of Nox2 and MCP-1 by stimulation with plasma from NTX mice. Our data suggest that renal disorder results in ventricular dysfunction and deteriorates remodeling after MI through excessive RAS activation. Moreover, renin inhibition improved the changes caused by cardiorenal syndrome.

Curcumin induces Nrf2 nuclear translocation and prevents glomerular hypertension, hyperfiltration, oxidant stress, and the decrease in antioxidant enzymes in 5/6 nephrectomized rats

Renal injury resulting from renal ablation induced by 5/6 nephrectomy (5/6NX) is associated with oxidant stress, glomerular hypertension, hyperfiltration, and impaired Nrf2-Keap1 pathway. The purpose of this work was to know if the bifunctional antioxidant curcumin may induce nuclear translocation of Nrf2 and prevents 5/6NX-induced oxidant stress, renal injury, decrease in antioxidant enzymes, and glomerular hypertension and hyperfiltration. Four groups of rats were studied: (1) control, (2) 5/6NX, (3) 5/6NX +CUR, and (4) CUR (n = 8–10). Curcumin was given by gavage to NX5/6 +CUR and CUR groups (60 mg/kg/day) starting seven days before surgery. Rats were studied 30 days after NX5/6 or sham surgery. Curcumin attenuated 5/6NX-induced proteinuria, systemic and glomerular hypertension, hyperfiltration, glomerular sclerosis, interstitial fibrosis, interstitial inflammation, and increase in plasma creatinine and blood urea nitrogen. This protective effect was associated with enhanced nuclear translocation of Nrf2 and with prevention of 5/6NX-induced oxidant stress and decrease in the activity of antioxidant enzymes. It is concluded that the protective effect of curcumin against 5/6NX-induced glomerular and systemic hypertension, hyperfiltration, renal dysfunction, and renal injury was associated with the nuclear translocation of Nrf2 and the prevention of both oxidant stress and the decrease of antioxidant enzymes.

Sildenafil treatment prevents glomerular hypertension and hyperfiltration in rats with renal ablation

BACKGROUND

Sildenafil treatment ameliorates progressive renal injury resulting from extensive renal ablation; however, modifications induced by sildenafil in the glomerular hemodynamic pathophysiology of the remnant kidney have not been investigated.

AIM

To determine the effects of sildenafil in the glomerular microcirculation and their relation to histological damage in the renal ablation model.

METHODS

Micropuncture studies were performed 60 days after 5/6 nephrectomy in rats that received no treatment, sildenafil (5 mg/kg/day) and reserpine, hydralazine and hydrochlorothiazide to maintain the blood pressure within normal levels. Sham-operated rats untreated and treated with sildenafil served as controls.

RESULTS

As expected, renal ablation induced systemic and glomerular hypertension, hyperfiltration, proteinuria, glomerulosclerosis and tubulointerstitial inflammatory damage in the remnant kidney. Sildenafil treatment prevented single-nephron hyperfiltration and hypertension, suppressed renal arteriolar remodeling, ameliorated systemic hypertension and proteinuria, increased urinary excretion of cGMP and NO(2)(-)/NO(3)(-), decreased oxidative stress and improved histological damage in the remnant kidney. Normalization blood pressure with reserpine, hydralazine and hydrochlorothiazide did not modify glomerular hemodynamics, proteinuria or histological changes induced by renal ablation.

CONCLUSIONS

Beneficial effects of sildenafil in the remnant kidney are associated with a reduction in the arteriolar remodeling, renal inflammatory changes and prevention of changes in the glomerular microcirculation.

Strategies to prevent or reduce acute and chronic kidney injury in liver transplantation

Acute kidney injury (AKI) has a major impact on short- and long-term survival in liver transplant (LT) patients. There is no currently accepted uniform definition of AKI, which would facilitate standardization of the care of patients with AKI and to improve and enhance collaborative research efforts. New promising biomarkers such as neutrophil gelatinase-associated lipocalin or kidney injury molecule-1 have been developed for the prevention of delayed AKI treatment. Early dialysis has been shown to be beneficial in patients with AKI stage III according to the classification of the Acute Kidney Injury Network, whereas treatment with loop diuretics or dopamine is associated with worse outcome. The mainstay for the prevention of AKI seems to be avoidance of volume depletion and maintenance of a mean arterial pressure >65 mmHg. Although the aetiology of chronic kidney disease in transplant recipients may be multifactorial, calcineurin-inhibitor (CNI)-induced nephrotoxicity significantly contributes to the development of renal dysfunction over time after LT. The delayed introduction of CNI at minimal doses has shown to be safe and effective for the preservation of kidney function. Other strategies to overcome CNI nephrotoxicity include CNI minimization protocols or CNI withdrawal and conversion to mycophenolate mofetil or the mammalian target of rapamycin inhibitor-based immunosuppressive regimens. However, CNI avoidance may bear a higher rejection risk. Thus, more results from randomized-controlled studies are urgently warranted to determine which drug combinations are the most beneficial approaches for the potential introduction of CNI-free immunosuppressive regimens.

Association between circulating specific leukocyte types and incident chronic kidney disease: the Atherosclerosis Risk in Communities (ARIC) study

Progressive renal fibrosis is a characteristic of all the diseases that cause renal failure and is invariably accompanied by a prominent leukocyte infiltration in the kidney. The goal of this study was to determine the association between the circulating specific leukocyte types and incident chronic kidney disease (CKD). In a cohort of 10,056 middle-aged white and African American adults, levels of circulating neutrophils, lymphocytes, and monocytes were measured at baseline; blood pressure (BP) and serum creatinine were measured and estimated glomerular filtration rate (eGFR) was calculated at baseline and 3 and 9 years later; and surveillance for first hospitalization or death with CKD was carried out over a mean follow-up of 7.4 years (maximum, 11.9 years). Increased neutrophil levels and decreased lymphocyte levels were significantly associated with greater CKD incidence after adjustment for covariates. African Americans tended to have similar but stronger patterns of association between circulating leukocytes and CKD incidence than whites, although the differences between race groups were not statistically significant. We also found that eGFR and BP were higher at each visit in African Americans than whites between ages 45 and 65. These findings support a potential role for circulating specific leukocytes in the pathogenesis of kidney dysfunction, especially in African Americans, indicating the leukocyte-related renal mechanism of essential hypertension (HT).

Calcineurin inhibitor-free immunosuppression in pediatric renal transplantation: a viable option?

The introduction, in the mid-1980s, of calcineurin inhibitors - namely ciclosporin (cyclosporine) and later tacrolimus - has significantly improved short-term renal graft survival by lowering acute rejection rates in both adult and pediatric kidney transplantation. Nonetheless, long-term transplant survival is still not satisfactory, with calcineurin inhibitor-induced chronic nephrotoxicity being one of the main causes of progressive nephron loss and declining renal transplant function. Hence, different immunosuppressant regimens have been proposed to avoid or ameliorate calcineurin inhibitor-induced nephrotoxicity. These comprise the use of non-depleting or depleting antibodies for calcineurin inhibitor minimization, calcineurin inhibitor avoidance, or calcineurin inhibitor withdrawal from mycophenolate mofetil-based immunosuppressant protocols. De novo use of a mammalian target of rapamycin (mTOR) inhibitor (sirolimus or everolimus) or conversion from a calcineurin inhibitor to an mTOR inhibitor may constitute another therapeutic option to avoid or reduce calcineurin inhibitor-induced nephrotoxicity. To date, complete calcineurin inhibitor avoidance seems to be inappropriate because other relatively potent immunosuppressant agents such as lymphocyte-depleting antibodies are needed for rejection prophylaxis, which are frequently accompanied by a higher incidence of infections and an unacceptably high acute rejection rate under calcineurin inhibitor avoidance. In some studies, calcineurin inhibitor withdrawal in adult and pediatric kidney allograft recipients with stable or declining transplant function has been associated with an amelioration of renal function; however, this is attained at the cost of a higher acute rejection rate in 10-20% of patients. It has been frequently stressed that conversion from a calcineurin inhibitor-based regimen to an mTOR inhibitor-based immunosuppressant regimen should be performed early (e.g. 3 or 6 months post-transplant) in patients with well-preserved renal transplant function without significant proteinuria in order to prevent, or at least limit, calcineurin inhibitor-induced tissue damage and provide long-term benefit. It should be borne in mind though that the use of an mTOR inhibitor carries the risk of potential adverse events such as aggravation of proteinuria, hyperlipidemia, myelosuppression, and hypergonadotropic hypogonadism. Even though everolimus may be better tolerated than sirolimus, studies on everolimus for calcineurin inhibitor-free immunosuppression in the pediatric kidney transplant patient population are lacking. At present, the safest therapeutic strategy for pediatric renal allograft recipients with chronic calcineurin inhibitor-induced nephrotoxicity appears to be a mycophenolate mofetil-based regimen with low-dose calcineurin inhibitor therapy and corticosteroids; available published data show that dual immunosuppression with mycophenolate mofetil and corticosteroids, as well as an mTOR inhibitor plus mycophenolate mofetil plus corticosteroid-based regimens, are associated with an increased risk of acute rejection episodes. In individual patients with evidenced chronic allograft dysfunction and over-immunosuppression leading to recurrent infections, dual maintenance immunosuppression with mycophenolate mofetil and corticosteroids may be appropriate. As stated in the annual report issued by the North American Pediatric Renal Trials and Collaborative Studies (NAPRTCS) Registry, currently the most popular immunosuppressant protocol consists of a calcineurin inhibitor combined with mycophenolate mofetil and corticosteroids: 59.1% and 53.2% of patients with a functioning graft receive a calcineurin inhibitor plus mycophenolate mofetil plus corticosteroid-based immunosuppression at 1 and 5 years post-transplant, respectively. 91.4% and 87.8% of patients are administered a calcineurin inhibitor-containing regimen 1 and/or 5 years after transplantation, respectively. Undoubtedly, the use of calcineurin inhibitor-free immunosuppressant regimens with or without antibody induction, plus an mTOR inhibitor and mycophenolate mofetil, requires more comprehensive long-term investigations to determine whether acceptable rejection rates and conservation of renal function can be achieved.

Histological progression of chronic renal allograft injury comparing sirolimus and mycophenolate mofetil-based protocols. A single-center, prospective, randomized, controlled study

In an effort to mitigate progression of IF/TA associated with chronic renal allograft injury, we hypothesize that adjuvant immunosuppression with sirolimus (SRL) will delay progression compared with MMF. Subjects 5-17 yr old, >1-yr post-transplant with mild or moderate IF/TA (Banff criteria) and tacrolimus dose minimization were randomized to continue MMF or convert to SRL and followed for two yr. For the entire cohort (n = 20), there was significant progression of %GGS, ci, ct, cv, and ah scores over the follow-up period (p < 0.05). There was no difference in rates of progression of Banff scores, %GGS, or % IF over two yr between the two groups, though power was low. Both groups exhibited similar rates of eGFR decline (MMF: -12.3 vs. SRL: -11.8 mL/min/1.73 m²/yr), which was correlated with ct score (p < 0.05). The SRL group had more episodes of acute allograft dysfunction and oral ulcers. Proteinuria at 24 months was significantly increased in the SRL group (6/9 subjects) but was not correlated with eGFR or %GGS. We conclude that neither MMF nor SRL, combined with low-dose tacrolimus, was effective at mitigating progressive histological changes or functional decline associated with chronic renal allograft injury.

The anti-fibrotic effect of mycophenolic acid-induced neutral endopeptidase

Mycophenolic acid (MPA) appears to have anti-fibrotic effects, but the molecular mechanisms underlying this are unknown. We prospectively studied 35 stable kidney transplant recipients maintained on cyclosporine and azathioprine. We converted 20 patients from azathioprine to enteric-coated mycophenolate sodium (EC-MPS) and continued the remaining 15 patients on azathioprine. Exploratory mRNA expression profiling, performed on five randomly selected EC-MPS patients, revealed significant upregulation of neutral endopeptidase (NEP), which is an enzyme that degrades angiotensin II. We confirmed these microarray data by measuring levels of NEP expression in all subjects; in addition, we found that NEP gene expression correlated inversely with proteinuria. In an additional 33 patients, glomerular and tubular NEP protein levels from renal graft biopsies were significantly higher among the 13 patients receiving cyclosporine + EC-MPS than among the 12 patients receiving cyclosporine + azathioprine or 8 patients receiving cyclosporine alone. Glomerular NEP expression inversely correlated with glomerulosclerosis and proteinuria, and tubular NEP expression inversely correlated with interstitial fibrosis. Incubation of human proximal tubular cells with MPA increased NEP gene expression in a dose- and time-dependent manner. Moreover, MPA reduced angiotensin II-induced expression of the profibrotic factor plasminogen activator inhibitor-1, and a specific NEP inhibitor completely reversed this effect. Taken together, our data suggest that MPA directly induces expression of neutral endopeptidase, which may reduce proteinuria and slow the progression of renal damage in kidney transplant recipients.

Treatment strategies to minimize or prevent chronic allograft dysfunction in pediatric renal transplant recipients: an overview

Long-term allograft survival poses a major problem in pediatric renal transplantation, with allograft nephropathy being the principal cause of graft failure after the first post-transplant year. The mechanisms of nephron loss resulting in graft dysfunction are multiple, comprising both immunologic factors such as acute and chronic antibody- or T-cell-mediated rejection and non-immunologic components. The latter include peri-transplant injuries and renovascular lesions (renal artery stenosis, thrombosis) as well as cardiovascular risk factors such as arterial hypertension and hyperlipidemia. Another relevant issue leading to progressive nephron loss and declining kidney transplant function is acute and chronic nephrotoxicity induced by the calcineurin inhibitors (CNIs) ciclosporin (cyclosporine microemulsion) and tacrolimus. Furthermore, the presence of an abnormal lower urinary tract as well as bacterial (recurrent pyelonephritis) and viral (cytomegalovirus [CMV], polyomavirus [BK virus; BKV]) infections are crucial factors involved in the incidence of chronic allograft dysfunction and graft failure. Renovascular lesions and lower urinary tract obstruction are typical indicators for surgical intervention. The aim of treatment in pediatric patients with renal failure secondary to a dysfunctional lower urinary tract is to create a sterile, continent, and nonrefluxive reservoir. Surgical techniques such as bladder augmentation and the introduction of intermittent catheterization and anticholinergic therapy have significantly improved graft outcome. Arterial hypertension, another factor responsible for graft function deterioration in pediatric renal transplant recipients, is controlled preferably by the use of angiotensin converting enzyme (ACE) inhibitors or angiotensin II receptor antagonists, which are known to possess nephroprotective properties in addition to their potent antihypertensive effects. Although treatment of subclinical rejection with augmented immunosuppression has been associated with better graft survival, an increase of the immunosuppressive level to avoid subclinical rejection should be weighed against the risk of infection. The majority of viral infections affecting kidney allografts are caused by CMV and BKV. Antiviral CMV prophylaxis or pre-emptive therapy with ganciclovir has been shown to have beneficial effects in the pediatric renal transplant population. Treatment of BKV-induced nephropathy is based on reduction of the immunosuppressant therapy, although specific antiviral agents such as cidofovir and leflunomide are known to inhibit BKV. However, cidofovir itself is nephrotoxic and should therefore be administered cautiously to pediatric renal transplant patients. Since CNIs are likewise known for their nephrotoxic effects, especially with long-term use, alteration of the immunosuppressant regimen is necessary in case of deteriorating graft function due to CNI-induced histopathologic changes. Complete CNI avoidance seems inappropriate because, in this situation in pediatric renal transplant recipients, other relatively potent immunosuppressant agents such as lymphocyte-depleting antibodies, which are frequently accompanied by a higher incidence of infections, are needed for rejection prophylaxis. CNI withdrawal and switching of the immunosuppressant regimen from CNI therapy to sirolimus may be an option for some pediatric renal transplant patients with less advanced graft function deterioration. Nevertheless, potential adverse events such as aggravation of proteinuria, hyperlipidemia, myelosuppression, and hypergonadotropic hypogonadism have to be considered, and controlled studies are lacking. At present, an immunosuppressant maintenance therapy composed of low-dose tacrolimus or ciclosporin (CNI minimization) and mycophenolate mofetil with low-dose corticosteroids appears to be the most promising strategy to adopt in pediatric renal transplant recipients at low or normal immunologic risk.

Postischemic inflammatory syndrome: a critical mechanism of progression in diabetic nephropathy

Diabetes is a major epidemic, and diabetic nephropathy is the most common cause of end-stage renal disease. Two critical components of diabetic nephropathy are persistent inflammation and chronic renal ischemia from widespread vasculopathy. Moreover, acute ischemic renal injury is common in diabetes, potentially causing chronic kidney disease or end-stage renal disease. Accordingly, we tested the hypothesis that acute renal ischemia accelerates nephropathy in diabetes by activating proinflammatory pathways. Lean and obese-diabetic ZS rats (F(1) hybrids of spontaneously hypertensive heart failure and Zucker fatty diabetic rats) were subjected to bilateral renal ischemia or sham surgery before the onset of proteinuria. The postischemic state in rats with obesity-diabetes was characterized by progressive chronic renal failure, increased proteinuria, and renal expression of proinflammatory mediators. Leukocyte number in obese-diabetic rat kidney was markedly increased for months after ischemia. Intrarenal blood flow velocity was decreased after ischemia in lean control and obese-diabetic rats, although it recovered in lean rats. At 2 mo after ischemia, blood flow velocity decreased further in sham-surgery and postischemia obese-diabetic rats, so that RBC flow velocity was only 39% of control in the obese-diabetic rats after ischemia. In addition, microvascular density remained depressed at 2 mo in kidneys of obese-diabetic rats after ischemia. Abnormal microvascular permeability and increases in interstitial fibrosis and apoptotic renal cell death were also more pronounced after ischemia in obese-diabetic rats. These data support the hypothesis that acute renal ischemia in obesity-diabetes severely aggravates chronic inflammation and vasculopathy, creating a self-perpetuating postischemia inflammatory syndrome, which accelerates renal failure.

The lymphocyte migration inhibitor FTY720 attenuates experimental hypertensive nephropathy

The lymphocyte migration inhibitor FTY720 attenuates experimental hypertensive nephropathy. Infiltration with lymphocytes is found in both immune and nonimmune chronic kidney diseases. In a rat model of immune-initiated progressive glomerulosclerosis, selective inhibition of lymphocyte infiltration by FTY720 showed significant beneficial effects on renal fibrosis. To test whether this translates into hypertensive nephropathy (HN), the lymphocyte migration inhibitor was administered to rats following nephrectomy. Two days after surgery, male Wistar rats were allocated to the following groups: Sham surgery, nephrectomy (HN), and HN + FTY720 (0.3 mg/kg body wt). Therapy was continued for 6 wk. Treatment with FTY720 was found to selectively reduce blood lymphocyte counts by 85% (P < 0.001 vs. HN) and renal lymphocyte infiltration (CD-3 positive cells) by 63% (P < 0.01 vs. HN) as was anticipated. Lymphocyte depletion went along with a significant reduction in proteinuria (-28%), whereas hypertensive systemic blood pressure remained unchanged (160 +/- 5 vs. 161 +/- 5 mmHg, P = not significant). The markedly increased histological tubulointerstitial and glomerular matrix protein accumulation, collagen, laminin, and fibronectin deposition were all significantly impeded in the FTY720-treated animals. The anti-fibrotic effects of FTY720 were paralleled by significant reductions in renal transforming growth factor (TGF)-beta overexpression, macrophage infiltration, and cell proliferation. In conclusion, the lymphocyte migration inhibitor FTY720 significantly limits histological and molecular fibrosis in a model of hypertensive nephropathy without affecting increased systemic blood pressure. Prevention of renal lymphocytes' infiltration by FTY720 was followed by significant reductions in TGF-beta overexpression, macrophage infiltration, and renal cell proliferation. These results suggest that infiltrating lymphocytes play an active, profibrotic role in the progression of hypertensive renal tissue injury.

Treatment with pyrrolidine dithiocarbamate improves proteinuria, oxidative stress, and glomerular hypertension in overload proteinuria

We evaluated whether the blockade of the proinflammatory transcription factor NF-kappaB would modify the oxidative stress, inflammation, and structural and hemodynamic alterations found in the kidney as a result of massive proteinuria. Twenty male Sprague-Dawley rats were injected with 2 g of BSA intraperitoneally daily for 2 wk. Ten of them received in addition the inhibitor of NF-kappaB activation pyrrolidine dithiocarbamate (PDTC; 200 mg.kg(-1).day(-1) sc) and the rest received vehicle. Seven rats that received intraperitoneal saline were used as controls. Glomerular hemodynamics were studied after 14 days. Markers of oxidative stress (NF-kappaB subunit p65+ cells, 3-nitrotyrosine, and 4-hydroxynonenal), inflammation (cortical CD68+ cells and NOS-II), and afferent arteriole damage were assessed by immunohistochemistry and morphometry. Activity of antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase was evaluated in renal cortex and medulla. Albumin overload induced massive proteinuria, oxidative stress with reduced activity of antioxidant enzymes, NF-kappaB activation, inflammatory cell infiltration, a significant presence of proteinaceous casts, systemic and glomerular hypertension, as well as arteriolar remodeling. Treatment with PDTC prevented or improved all of these findings. In this model of nephrotic syndrome, we demonstrate a key role for oxidative stress and inflammation in causing systemic and glomerular hypertension and proteinuria. Oxidative stress and inflammation may have a key role in accelerating renal injury associated with intense proteinuria.

Immune modulating therapy for IgA nephropathy: rationale and evidence

Our current understanding of the initial pathogenetic steps in IgA nephropathy (IgAN) provides relatively limited rationale for immunosuppressive therapy. However, it is conceivable that immunosuppressive drugs might affect secondary inflammatory events triggered by glomerular immune deposits or even proteinuria per se. Some, but not all, randomized clinical trials on either corticosteroid monotherapy, mycophenolate mofetil monotherapy, or immunosuppressive combination therapy have provided evidence for a benefit on either surrogate parameters such as proteinuria or hard end points such as renal failure. The central problem of these studies is that most were designed in the 1980s or 1990s, when recommendations for supportive therapy were strikingly different from those of today. In the meantime an equal number of randomized clinical studies reporting a benefit of supportive therapy has been published only regarding patients with IgAN and, unfortunately, no head-to-head comparisons of these 2 approaches currently are available. Several ongoing clinical trials may help to resolve this dilemma. Until the data of such studies become available, a pragmatic approach is to first optimize supportive therapy and reserve immunosuppressive medication for those patients failing a supportive approach and remaining at risk for progressive loss of renal function.

Pathogenesis of essential hypertension: historical paradigms and modern insights

Since its first identification in the late 1800s, a variety of etiologies for essential hypertension have been proposed. In this paper we review the primary proposed hypotheses in the context of both the time in which they were proposed as well as the subsequent studies performed over the years. From these various insights, we propose a current paradigm to explain the renal mechanisms underlying the hypertension epidemic today. Specifically, we propose that hypertension is initiated by agents that cause systemic and intrarenal vasoconstriction. Over time intrarenal injury develops with microvascular disease, interstitial T cell and macrophage recruitment with the induction of an autoimmune response, with local angiotensin II formation and oxidant generation. These changes maintain intrarenal vasoconstriction and hypoxia with a change in local vasoconstrictor-vasodilator balance favoring sodium retention. Both genetic and congenital (nephron number) mechanisms have profound influence on this pathway. As blood pressure rises, renal ischemia is ameliorated and sodium balance restored completely (in salt-resistant) or partially (in salt-sensitive) hypertension, but at the expense of a rightward shift in the pressure natriuresis curve and persistent hypertension.

Renoprotective and antihypertensive effects of S-allylcysteine in 5/6 nephrectomized rats

Progressive renal damage and hypertension are associated with oxidative and nitrosative stress. On the other hand, S-allylcysteine (SAC), the most abundant organosulfur compound in aged garlic extract (AG), has antioxidant properties. The effects of SAC and AG on blood pressure, renal damage, and oxidative and nitrosative stress were studied in five-sixths nephrectomized rats treated with SAC (200 mg/kg ip) and AG (1.2 ml/kg ip) every other day for 30 days. Proteinuria and serum creatinine and blood urea nitrogen concentrations were measured on days 0, 5, 10, 15, and 30, and systolic blood pressure was recorded on days 0, 15, and 30. The degree of glomerulosclerosis and tubulointerstitial damage, the immunostaining for inducible nitric oxide synthase, 3-nitrotyrosine, poly(ADP-ribose), and the subunits of NADPH oxidase p22phox and gp91phox, and the activity of SOD were determined on day 30. SAC and AG reduced hypertension, renal damage, and the abundance of inducible nitric oxide synthase, 3-nitrotyrosine, poly(ADP-ribose), p22phox, and gp91phox and increased SOD activity. Our data suggest that the antihypertensive and renoprotective effects of SAC and AG are associated with their antioxidant properties and that they may be used to ameliorate hypertension and delay the progression of renal damage.

Mycophenolate mofetil is associated with altered expression of chronic renal transplant histology

Mycophenolate mofetil (MMF) reduces acute rejection in controlled trials of kidney transplantation and is associated with better registry graft survival. Recent experimental studies have demonstrated additional antifibrotic properties of MMF, however, human histological data are lacking. We evaluated sequential prospective protocol kidney biopsies from two historical cohorts treated with cyclosporine (CSA)-based triple therapy including prednisolone and either MMF (n = 25) or azathioprine (AZA, n = 25). Biopsies (n = 360) were taken from euglycemic kidney-pancreas transplant recipients. Histology was independently assessed by the Banff schema and electron microscopic morphometry. MMF reduced acute rejection and OKT3 use (p < 0.05) compared with AZA. MMF therapy was associated with limited chronic interstitial fibrosis, striped fibrosis and periglomerular fibrosis (p < 0.05-0.001), mesangial matrix accumulation (p < 0.01), chronic glomerulopathy scores (p < 0.05) and glomerulosclerosis (p < 0.05). MMF was associated with delayed expression of CSA nephrotoxicity, reduced arteriolar hyalinosis, striped fibrosis and tubular microcalcification (p < 0.05-0.001). The beneficial effects of MMF remained in recipients without acute rejection. Retrospective analysis shows that MMF therapy was associated with substantially reduced fibrosis in the glomerular, microvascular and interstitial compartments, and a delayed expression of CSA nephrotoxicity. These outcomes may be due to a limitation of immune-mediated injury and suggest a direct effect of reduced fibrogenesis.

Treatment strategies in pediatric solid organ transplant recipients with calcineurin inhibitor-induced nephrotoxicity

Although short-term kidney allograft survival has improved significantly since the introduction of the calcineurin inhibitors (CNI) cyclosporine A (CsA) and tacrolimus, long-term transplant survival remains a major concern, chronic allograft nephropathy (CAN) being the principal reason for graft loss after the first post-transplant year. This is particularly major for pediatric renal transplant recipients because of their higher life expectancy compared with adults. The mechanisms leading to CAN are multiple, including acute and chronic alloimmune responses and nephrotoxicity of CNIs. CNI-induced nephrotoxicity is also a long-term concern in other pediatric solid organ transplant recipients, such as liver and heart. Prevention of allograft nephropathy requires a balance of maintaining adequate immunosuppression, while avoiding the toxic effects of CNIs. Regimens that are based on mycophenolate mofetil (MMF) alone or in combination with newer agents may allow for reduced reliance on CNIs and thus may represent an effective treatment paradigm for long-term maintenance of a renal allograft. From the available data it appears that the currently safest treatment strategy in pediatric renal and heart transplant recipients with CNI toxicity is an MMF-based therapy with low-dose CNIs +/- low-dose steroids, while in pediatric liver transplant recipients, CNI-free MMF-based immunosuppressive therapy with or without steroids appears feasible in a significant subset of patients. In renal transplant recipients, the benefit of a CNI-free MMF/steroid therapy on renal function is gained at the cost of increased rejection in a subset of patients, although the relative importance of rejection vs. overall renal function requires further clinical investigation. The introduction of mammalian target of rapamycin (mTOR) inhibitors provides an opportunity for unique CNI-sparing regimens that combine two antiproliferative agents (MMF and TOR inhibitors). It is possible that a sirolimus-based CNI-free immunosuppressive regimen in terms of renal transplant survival is superior to CNI minimization, where the detrimental effects of CNIs on allograft function and structure are still operative, albeit to a lesser degree. Substitution of CNIs by mTOR inhibitors is therefore promising, but requires validation in long-term studies in large cohorts.

Effects of mycophenolate mofetil on cisplatin-induced renal dysfunction in rats

PURPOSE

Inflammation and oxidative stress are important events among the plethora of mechanisms involved in cisplatin (CDDP)-induced nephrotoxicity. The aim of this study was to evaluate the effect of mycophenolate mofetil (MMF), an immunosuppressive, in the protection against CDDP-induced renal dysfunction.

METHODS

Rats were divided into four groups; untreated-control group, CDDP-treated group (7 mg/kg, single intraperitoneal dose), MMF-treated group (40 mg/kg/day orally for 5 successive days) and the fourth group was treated with both drugs and MMF treatment was started 1 day prior to CDDP administration. Nephrotoxicity was assessed 7 days after the CDDP treatment by measuring serum indices of nephrotoxicity, kidney weight as a percentage of total body weight, kidney's tissue peroxidative alterations and total nitrate/nitrite concentration (NOx) and the results were confirmed histopathologically.

RESULTS

Rats treated with CDDP showed marked nephrotoxicity as evidenced from the significant increase in serum creatinine and urea levels and decrease in serum calcium and albumin levels. Kidneys of CDDP-treated rats showed significant increases in kidney weight and malondialdehyde (MDA) production level and decreases in total NOx concentration, glutathione peroxidase (GPx) activity and reduced glutathione (GSH) content levels. Histopathological assessment of kidneys of CDDP-treated rats revealed extensive tubular necrosis with "sloughing off" of the renal tubular lining cells, intratubular hyaline casts and mononuclear cell infiltration. Treatment with MMF significantly protected the rats against CDDP-induced nephrotoxicity. The rise in serum creatinine and urea levels, kidney weight and kidney tissue MDA production, depletion of "endogenous antioxidant reserve" including GPx activity and reduced GSH content levels and the deleterious histopathological changes induced by CDDP treatment were significantly mitigated by MMF treatment.

CONCLUSIONS

MMF treatment dramatically ameliorates CDDP-induced renal dysfunction.

Transient Improvement of Hypertension-Induced Chronic Renal Failure with Mycophenolate Mofetil Treatment

A young female with essential hypertension developed progressive azotemia; renal biopsy showed hypertensive nephrosclerosis with considerable tubulointerstitial disease and cellular infiltration. The addition of mycophenolate mofetil (MMF) to her antihypertensive treatment resulted in a dramatic improvement of renal function during the following three months. When the patient discontinued MMF treatment, end-stage renal failure rapidly developed. This patient represents the first report of the beneficial use of MMF in non-immune chronic renal disease and demonstrates that significant functional improvement may be obtained with the addition of MMF to the treatment of hypertensive nephrosclerosis for patients in whom there is significant tubulointerstitial inflammatory infiltration.

In vitro prevention of cyclosporin-induced cell contraction by mycophenolic acid

Nephrotoxicity is a major side-effect of cyclosporin A (CsA), which induces a vasoconstrictive response in vascular smooth muscle and mesangial cells. Mycophenolic acid (MPA) is used in combination with low-dose CsA to reduce nephrotoxicity. We previously demonstrated that MPA affected mesangial cell contractile response to angiotensin II or KCl. Aims of the present study were to evaluate if MPA can prevent CsA-induced contraction of human mesangial and aortic smooth muscle cells (ASMC). Using a morphoquantitative approach, we evidenced that pretreatment with MPA (1 microM) prevented the reduction of cell area induced by CsA within 30 min in both cell types. We then compared the expression of three main cytoskeleton proteins: tubulin, alpha-smooth actin (SMA) and basic calponin, in ASMC and in mesangial cells treated with MPA and/or CsA. CsA alone did not significantly change the expression level of these proteins neither in mesangial cells nor in ASMC. MPA decreased the expression level of tubulin in both mesangial cells and ASMC. Surprisingly, MPA, which stimulated SMA and calponin expression in mesangial cells, exerted an inhibitory effect on both contractile protein expression in ASMC. In conclusion, our results evidenced opposite effects of MPA on calponin and SMA protein expression in ASMC and in mesangial cells, despite similar antiproliferative properties, suggesting that sarcomeric protein expression is controlled by different intracellular mechanisms in mesangial and smooth muscle cells. However, MPA interferes in both cell types with the constrictive properties CsA, which may partially explain the protective effects of MPA against CsA nephrotoxicity.

Mild hyperuricemia induces vasoconstriction and maintains glomerular hypertension in normal and remnant kidney rats

BACKGROUND

Hyperuricemia has been associated with renal disease. Because glomerular hemodynamic alterations critically contribute to initiation and progression of renal disease, we evaluated the effect of mild hyperuricemia in glomerular microcirculatory changes in rats under normal conditions and with renal injury induced by subtotal renal ablation (RK).

METHODS

Hyperuricemia was induced in normal and remnant kidney (RK) rats on a normal sodium diet by administration of oxonic acid (OA). To prevent hyperuricemia, allopurinol (AP) was administered concomitantly. Glomerular hemodynamics were evaluated by micropuncture techniques. Systolic blood pressure (SBP), proteinuria, arterial morphology, and serum uric acid were measured. In RK rats, glomerulosclerosis, fibrosis, and inflammatory cell infiltration (CD5+) were also assessed.

RESULTS

In normal rats, hyperuricemia resulted in afferent arteriole thickening associated with renal cortical vasoconstriction [single nephron glomerular filtration rate (SNGFR) -35%, P < 0.05) and glomerular hypertension (P < 0.05). Allopurinol treatment prevented structural and functional alterations. In RK rats, hyperuricemia produced more renal vascular damage than control animals coupled with severe cortical vasoconstriction (SNGFR -40%, P < 0.05) and persistent glomerular hypertension. Allopurinol partially prevented cortical vasoconstriction, and fully prevented arteriolopathy and glomerular hypertension associated with significantly less infiltration of CD5+ cells.

CONCLUSION

Hyperuricemia induces arteriolopathy of preglomerular vessels, which impairs the autoregulatory response of afferent arterioles, resulting in glomerular hypertension. Lumen obliteration induced by vascular wall thickening produces severe renal hypoperfusion. The resulting ischemia is a potent stimulus that induces tubulointerstitial inflammation and fibrosis, as well as arterial hypertension. These studies provide a potential mechanism by which hyperuricemia can mediate hypertension and renal disease.

Essential hypertension, progressive renal disease, and uric acid: a pathogenetic link?

Hypertension and hypertension-associated ESRD are epidemic in society. The mechanisms responsible for renal progression in mild to moderate hypertension and those groups most at risk need to be identified. Historic, epidemiologic, clinical, and experimental studies on the pathogenesis of hypertension and hypertension-associated renal disease are reviewed and an overview/hypothesis for the mechanisms involved in renal progression is presented. There is increasing evidence that hypertension may exist in one of two forms/stages. The first stage, most commonly observed in early or borderline hypertension, is characterized by salt-resistance, normal or only slightly decreased GFR, relatively normal or mild renal arteriolosclerosis, and normal renal autoregulation. This group is at minimal risk for renal progression. The second stage, characterized by salt-sensitivity, renal arteriolar disease, and blunted renal autoregulation, defines a group at highest risk for the development of microalbuminuria, albuminuria, and progressive renal disease. This second stage is more likely to be observed in blacks, in subjects with gout or hyperuricemia, with low level lead intoxication, or with severe obesity/metabolic syndrome. The two major mechanistic pathways for causing impaired autoregulation at mild to moderate elevations in BP appear to be hyperuricemia and/or low nephron number. Understanding the pathogenetic pathways mediating renal progression in hypertensive subjects should help identify those subjects at highest risk and may provide insights into new therapeutic maneuvers to slow or prevent progression.

Why is proteinuria an ominous biomarker of progressive kidney disease?

Progressive tubule injury and interstitial fibrosis frequently accompany glomerulopathies associated with proteinuria. Clinical experience indicates that higher levels of proteinuria prior to, as well as after initiation of treatment predict more rapid decline in renal function and more pronounced tubulointerstitial injury. It has been proposed that filtration of potentially tubulotoxic plasma proteins is responsible for the observed correlations between proteinuria and progression (i.e., proteinuria is a cause and not only a consequence of progressive renal injury). Numerous attempts have been made to identify the species of putative tubulotoxic proteins in this progressive injury process, but much uncertainty persists. These uncertainties stem from nonphysiologic exposure of apical cell surfaces to proteins in vitro, the extremely high concentrations of various proteins tested in vitro, and the nonuniformity of end points measured. Furthermore, there is often a lack of correlation between in vitro and in vivo findings, and a lack of uniformity of results even for seemingly similar in vitro experiments. Less controversy is evident in the potential pathways whereby injured tubules evoke a tubulointerstitial inflammatory and fibrotic response, with many in vivo models serving to incriminate excessive cytokine and chemokine production, infiltration of various inflammatory cells, and the balance between apoptosis and cell proliferation. Despite many years of concerted efforts, we believe it is still unclear whether proteinuria is a cause (and if so, which species of protein), or only a consequence of progressive renal injury. Nevertheless, pending the resolution of these uncertainties by more decisive and unambiguous experimentation, the strongly predictive inverse relationship between level of proteinuria and long-term renal survival currently justifies aggressive antiproteinuric treatment strategies, with a goal of reducing protein excretion rate to the lowest level possible without the induction of symptoms or undue risk.

Selective lymphocyte inhibition by FTY720 slows the progressive course of chronic anti-thy 1 glomerulosclerosis

BACKGROUND

Progression is a hallmark of chronic renal disease and histologically characterized by fibrosis and inflammation of the tubulointerstitial compartment. To define the role of lymphocytes in this process, the novel lymphocyte-specific inhibitor FTY720 was administered to rats with anti-thy 1-induced chronic progressive glomerulosclerosis. In this model, the initial and short-term inflammatory glomerular injury progresses self-perpetuatedly toward tubulointerstitial fibrosis by not primarily immune-mediated, intrarenal mechanisms.

METHODS

Chronic progressive glomerulosclerosis was induced by murine anti-thy 1 antibody injection into uninephrectomized rats. Treatment with FTY720 (0.3 mg/kg body weight) was started 7 days after disease induction. Proteinuria was measured every 4 weeks. In week 20, the following parameters were determined: blood lymphocyte number, kidney function, both glomerular and tubulointerstitial histologic matrix accumulation, protein expression of transforming growth factor-beta1 (TGF-beta1), fibronectin, and plasminogen activator inhibitor-1 (PAI-1) as well as infiltration with macrophages and lymphocytes.

RESULTS

Treatment with FTY720 lowered blood lymphocyte count and renal lymphocyte infiltration highly significantly. In comparison to the untreated chronic progressive glomerulosclerosis animals, the lymphocyte depletion achieved significantly limited the progression of the disease, as shown by lowered proteinuria, tubulointerstitial matrix expansion, and TGF-beta1, fibronectin, and PAI-1 expression, as well as improved renal function. Glomerular matrix protein expression and accumulation was moderately lowered by FTY720. Glomerular macrophage infiltration was not, tubulointerstitial macrophage infiltration was moderately, but not significantly, decreased by FTY720 treatment.

CONCLUSION

Lymphocyte depletion by FTY720 limits the progression of anti-thy 1-induced glomerulosclerosis toward chronic tubulointerstitial fibrosis and renal insufficiency. The data suggest that lymphocytes actively participate in the progression of chronic experimental kidney disease, and that FTY720 may be a novel approach to slow the progressive course of human chronic renal diseases.

Hemodynamics of hyperuricemia

Prolonged hyperuricemia is associated with the development of hypertension, renal arteriolosclerosis, glomerulosclerosis, and tubulointerstitial injury. It confers a greater risk than proteinuria for developing chronic renal disease and is associated with the development of hypertension. Mild chronic hyperuricemia without intrarenal crystal deposition was induced in rats by inhibiting uricase with oxonic acid. Hyperuricemic rats developed hypertension, afferent arteriolar thickening, and mild renal interstitial fibrosis. Additionally, hyperuricemia accelerated renal damage and vascular disease in rats undergoing renal ablation. To better understand the role of hyperuricemia in the kidney, micropuncture studies were performed. Hyperuricemia resulted in renal cortical vasoconstriction (single nephron glomerular filtration rate (SNGFR) 35%, P < .05) and glomerular hypertension (P < .05). The possibility that hyperuricemia could modify renal hemodynamic disturbances during progression of renal disease was tested in rats with 5/6 nephrectomy. Hyperuricemia accentuated the renal vascular damage and caused cortical vasoconstriction (SNGFR 40%, P < .05) and persistent glomerular hypertension. In conclusion, hyperuricemia impairs the autoregulatory response of preglomerular vessels, resulting in glomerular hypertension. Lumen obliteration induced by vascular wall thickening results in severe vasoconstriction. The resulting ischemia is a potent stimulus that induces tubulointerstitial inflammation and fibrosis as well as arterial hypertension.

Mycophenolate mofetil in IgA nephropathy: results of a 3-year prospective placebo-controlled randomized study

BACKGROUND

Because humoral immunity is believed to play a pivotal role in the pathogenesis of IgA nephropathy (IgAN), a prospective placebo-controlled randomized study was started in patients with IgAN using mycophenolate mofetil (MMF).

METHODS

A total of 34 patients with IgAN were treated with salt intake restriction, angiotensin-converting enzyme (ACE) inhibition and MMF 2 g per day (N= 21) or placebo (N= 13). After 36 months of follow-up clinical, biochemical, and radiologic data were analyzed using linear mixed models for longitudinal data and Kaplan-Meier survival analysis.

RESULTS

Therapy had to be stopped prematurely in five patients. Two patients (MMF group) evolved to end-stage renal disease (ESRD). There was no difference between groups in the percentage of patients with a decrease of 25% or more in the inulin clearance or with a serum creatinine increase of 50% or more over 3 years. There was also no significant difference between groups in annualized rate of change of serum creatinine, computed by linear regression analysis. No significant difference was noted between groups for inulin clearance, serum creatinine, proteinuria, blood pressure, or other parameters of renal function. Hemoglobin and C-reactive protein were significantly lower in the MMF group compared with the placebo group. As a function of time, a significant decline in both groups was noted of proteinuria, parenchymal thickness of the kidneys and C3d.

CONCLUSION

In patients with IgAN at risk for progressive disease, no beneficial effect of 3-year treatment with MMF 2 g per day could be demonstrated on renal function/outcome or proteinuria. However, larger randomized studies are needed to confirm or reject these results.

Disturbances in Renal Autoregulation and the Susceptibility to Hypertension-Induced Chronic Kidney Disease

The risk of developing chronic kidney disease in the setting of hypertension varies among patient populations. Black hypertensive patients have an increased risk of developing hypertension-induced chronic kidney disease even after taking into account socioeconomic factors. There is evidence to suggest that the kidney is intrinsically more susceptible to the damaging effects of hypertension in black patients. This susceptibility can be traced to disturbances in the way the kidney autoregulates. Impaired renal autoregulation may be the renal manifestation of a more widespread abnormality in endothelial function. Other conditions that can impair renal autoregulation and add to the risk of chronic kidney disease include low birth weight, obesity, insulin resistance, hyperuricemia, and hypercholesterolemia. To minimize the risk of chronic kidney disease in patients with impaired renal autoregulatory capability, strict blood pressure control is required. There is indirect evidence that blocking the renin-angiotensin system may improve renal autoregulation.

Review of the immunosuppressant enteric-coated mycophenolate sodium

Enteric-coated mycophenolate sodium (EC-MPS; myfortic, Novartis Pharma AG) is an advanced formulation delivering mycophenolic acid (MPA). EC-MPS was designed to improve MPA-related upper gastrointestinal adverse events by delaying the release of MPA until reaching the small intestine. At a dose of 720 mg, EC-MPS exhibits equivalent MPA exposure (area under the concentration curve [AUC]) and maximal MPA concentration (C(max)) to mycophenolate mofetil (MMF; CellCept, Roche AG) 1000 mg. The time to maximal MPA concentration (T(max)) for EC-MPS is delayed relative to that for MMF, consistent with a functioning enteric coating. EC-MPS 720 mg b.i.d. has demonstrated therapeutic equivalence to MMF 1000 mg b.i.d. in renal transplant patients. Recent clinical trials have demonstrated that EC-MPS is as effective and safe as MMF in both de novo and maintenance renal transplant patients. Furthermore, studies have confirmed that maintenance patients can be safely converted from MMF to EC-MPS with no compromise of efficacy or safety. EC-MPS therefore presents physicians and patients with a valid alternative MPA therapy with a comparable efficacy and safety profile to MMF.

Angiotensin II-dependent induction of AT(2) receptor expression after renal ablation

Angiotensin (ANG) II can be associated with gene expression regulation. Thus we studied the possible role of ANG II in the regulation of AT(2) mRNA and protein expression. We utilized sham-operated renal ablation rats as well as renal ablation rats pretreated during the first 7 days of the development of renal damage with either the angiotensin-converting inhibitor ramipril, the AT(1) receptor antagonist losartan, or the AT(2) receptor antagonist PD-123319. Renal tissue was analyzed for histological changes and expression of AT(2) receptor mRNA (by RT-PCR) and protein (by immunohistochemistry). To explore the physiological role of AT(2) receptor overexpression in the development of renal damage, blood pressure, urinary protein excretion, and renal damage were evaluated. A time-dependent increase in the expression of AT(2) receptor mRNA and protein was observed at 7, 15, and 30 days after renal ablation. Because these effects were already evident at day 7, the effects of ramipril, losartan, or PD-123319 were tested at this time. The ramipril group and the PD-123319-pretreated group showed inhibition of AT(2) receptor expression, whereas the losartan-pretreated group showed a further increase in AT(2) receptor expression. Inhibition of the AT(2) receptor during renal ablation was associated with increased renal damage and a further increase in the blood pressure. This suggests that overexpression of AT(2) receptors after renal ablation is modulated by ANG II through its own AT(2) receptor and that functional expression of this effect may represent a counterregulatory mechanism to modulate the renal damage induced by renal ablation.

Oxidative stress, renal infiltration of immune cells, and salt-sensitive hypertension: all for one and one for all

Recent evidence indicates that interstitial infiltration of T cells and macrophages plays a role in the pathogenesis of salt-sensitive hypertension. The present review examines this evidence and summarizes the investigations linking the renal accumulation of immune cells and oxidative stress in the development of hypertension. The mechanisms involved in the hypertensive effects of oxidant stress and tubulointerstitial inflammation, in particular intrarenal ANG II activity, are discussed, focusing on their potential for sodium retention. The possibility of autoimmune reactivity in hypertension is raised in the light of the proinflammatory and immunogenic pathways stimulated by the interrelationship between oxidant stress and inflammatory response. Finally, we present some clinical considerations derived from the recognition of this interrelationship.

Mycophenolate mofetil ameliorates arteriolopathy and decreases transforming growth factor-beta1 in chronic cyclosporine nephrotoxicity

Afferent arteriolopathy is the most characteristic lesion of chronic cyclosporine (CsA) nephrotoxicity. We investigated the effect of therapeutic doses of mycophenolate mofetil (MMF) in a model of chronic CsA nephrotoxicity where transforming growth factor-beta (TGF-beta) was shown to play a central role. Rats treated with vehicle, MMF 10 mg/kg/day, CsA 10 mg/kg/day or CsA + MMF were sacrificed at 7 or 28 days. Physiologic and histologic changes were studied in addition to TGF-beta1 mRNA and protein expressions, and mRNA expression of plasminogen activator inhibitor-1 (PAI-1) and the extracellular matrix (ECM) proteins biglycan and types I and IV collagen. While MMF markedly ameliorated afferent arteriolopathy, it had no significant effect on interstitial fibrosis and tubular atrophy. In addition, MMF treatment reduced both TGF-beta1 mRNA and protein levels by 39% and 32%, respectively (p < 0.05 vs. CsA only). The expression of the ECM proteins followed that of TGF-beta1 and was significantly decreased with MMF; a similar effect was observed with PAI-1, suggesting an increase in ECM degradation. These results suggest that MMF exerts a beneficial effect on CsA arteriolopathy and that it decreases TGF-beta1. While this drug combination may be useful clinically, long-term studies are needed to determine if MMF has a lasting benefit.

Management of Glomerular Proteinuria: A Commentary

ABSTRACT. It is widely accepted that proteinuria reduction is an appropriate therapeutic goal in chronic proteinuric kidney disease. Based on large randomized controlled clinical trials (RCT), ACE inhibitor (ACEI) and angiotensin receptor blocker (ARB) therapy have emerged as the most important antiproteinuric and renal protective interventions. However, there are numerous other interventions that have been shown to be antiproteinuric and, therefore, likely to be renoprotective. Unfortunately testing each of these antiproteinuric therapies in RCT is not feasible. The nephrologist has two choices: restrict antiproteinuric therapies to those shown to be effective in RCT or expand the use of antiproteinuric therapies to include those that, although unproven, are plausibly effective and prudent to use. The goal of this work is to provide the documentation needed for the nephrologist to choose between these strategies. This work describes 25 separate interventions that are either antiproteinuric or may block injurious mechanisms of proteinuria. Each intervention is assigned a level of recommendation (Level 1 is the highest; Level 3 is the lowest) according to the strength of the evidence supporting its antiproteinuric and renoprotective efficacy. Pathophysiologic mechanisms possibly involved are also discussed. The number of interventions at each level of recommendation are: Level 1, n = 7; Level 2, n = 9; Level 3, n = 9. Our experience indicates that we can achieve in most patients the majority of Level 1 and many of the Level 2 and 3 recommendations. We suggest that, until better information becomes available, a broad-based, multiple-risk factor intervention to reduce proteinuria can be justified in those with progressive nephropathies. This work is intended primarily for clinical nephrologists; therefore, each antiproteinuria intervention is described in practical detail.

Cytoskeletal Reorganization by Mycophenolic Acid Alters Mesangial Cell Migration and Contractility

Cytoskeleton alterations are a hallmark of mesangial cell activation during glomerulosclerosis. The aim of this study was to investigate whether mycophenolic acid (MPA) affects cytoskeletal organization and motility of human mesangial cells. Using the IP15 cell line, we found that treatment with 1 μmol/L MPA inhibited both receptor-dependent (angiotensin II) and receptor-independent (KCl) contractile responses, as well as serum-induced migration activity, suggesting alterations in the intracellular mechanisms that control mesangial cell motility. Immunofluorescence studies of MPA-treated cells provided evidence for decreased membrane disassembly/reassembly of α-smooth muscle actin and F-actin fibers, which was correlated with sustained quantitative and qualitative modifications of actin-associated proteins: calponin was overexpressed and became associated with actin fibers, whereas phosphorylation levels of cofilin and myosin light chain increased, suggesting both an activation of the mechanisms responsible for actin polymerization and an inhibition of actin-depolymerizing processes. These observations support a stabilizing effect of MPA on the mesangial actin cytoskeleton, which constitutes an additive action by which MPA, beyond its anti-inflammatory, antiproliferative and antifibrotic properties, might protect against excessive mesangial activation in the context of various glomerulopathies and kidney transplantation.